During neurosurgical procedures, electrodes are commonly used to monitor electrical activity and stimulate and/or lesion neural tissue. Typically, electrodes are brought into the vicinity of cell membranes so that an electrical transition resistance (impedance) is created between the cells and the electrodes. Electrical stimulation of a malfunctioning neuron can be used to activate or reversibly block neural activity, while lesioning can be used to permanently disable neuronal activity.
The recent resurgence of procedures to stimulate and produce lesions in deep brain structures for the treatment of Parkinson's disease, tremor, and dystonia, has been due not only to a better understanding of functional neuroanatomy of the cells involved in these diseases, but also to the development of techniques for accurately localizing these cells. Microelectrode recording allows direct recording and characterization of the activity of neural cells and can be used to record individual cells at a spatial interval from a micron to 100 microns and in a frequency range from 600 Hz to 3000 Hz.
While microelectrodes provide the best means of localizing diseased cells, generally, microelectrodes must be inserted into the brain multiple times (e.g., at target sites separated by about 2 mm) to sufficiently characterize the physiology of a region which is to be stimulated or lesioned. Probes comprising groups of microelectrodes bundled together at high density (“multichannel microelectrodes”) increase the resolution of individual recording passes, and can stimulate/lesion and record a 20-200 μm radius around an insertion site. Typically, a multichannel microelectrode is inserted at a location, and when a site of pathology is identified, it is removed and replaced by a larger diameter macroelectrode (e.g., about 1.1 mm) which is used to validate target location and for subsequent stimulating and/or lesioning. However, even multichannel microelectrodes must be inserted and removed at least three to five times to obtain good target localization and macroelectrodes generally must be inserted separately.
Multichannel electrodes which combine the recording functions of microelectrodes and the stimulating functions of macroelectrodes have been reported (see, e.g., U.S. Pat. Nos. 5,282,468, 2005/0246004, 2006/0003090, 7,010,356 and 2006/0095105). However, there remains a need for less intrusive custom configurable neurological probes that can simultaneously provide stimulation/lesioning and recording over a large field.